Fault diagnosis involves the detection, location and identification of faults. The objective of this work is detection of faults in a synchronous generator (SG) using the parity space approach. The method is based on building the fault indicators using analytical redundancy relationships. The proposed technique is successfully applied for external fault diagnosis of a 4-pole, 60-Hz, 208-V, 1.5-kVA laboratory synchronous generator using a three-phase sudden short-circuit fault.